The present embodiments relate to a method for irradiation planning for particle therapy of a target volume.
As a preliminary to any particle therapy treatment, an irradiation plan is determined. Essentially, the irradiation plan defines how the target volume is to be irradiated in order to apply the desired dosage distribution in the body. In the case of particle therapy, the number of particles to be applied may be determined for each target point or grid point in the target volume.
For this purpose, an iterative optimization method may be used for the irradiation planning. Owing to the complexity of the calculation, the iterative optimization method may sometimes take a long time and necessitate a large computational effort to determine an irradiation plan such that a particular desired dosage prescription is satisfied in terms of irradiation of the target volume and the surrounding organs.
In addition, this determination of a suitable irradiation plan is made more complicated by the fact that the internal anatomy of a patient may change over time. For example, target volumes within the abdomen may change position from day-to-day or over the course of several days or weeks. A typical organ that may be subject to a change of position is the prostate gland. Thus, the bladder that lies beside the prostate gland and the rectum that lies close to the prostate gland may have an effect on the position and the shape of the prostate gland, depending on the extent to which the bladder and/or the rectum are filled.
Hence, an irradiation plan that is calculated one day may no longer be optimal for irradiating the patient on another day.